Gesture recognition apparatus and control method of gesture recognition apparatus

ABSTRACT

A gesture recognition apparatus detecting a gesture from an image and generating for an object device an instruction corresponding to the gesture, the gesture recognition apparatus comprises an image acquiring unit configured to acquire an image; an object part extracting unit configured to extract an object part performing a gesture; an object part shape identifying unit configured to identify a shape of the extracted object part; a representative point determining unit configured to set a representative point that is a point representing a position of the object part; a gesture recognizing unit configured to recognize a gesture, based on a motion of the representative point; and a command generating unit configured to generate an instruction corresponding to the recognized gesture, wherein the representative point determining unit determines a position of a representative point corresponding to the object part, using the identified shape of the object part.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a gesture recognition apparatus thatrecognizes an input operation with a gesture.

2. Description of the Related Art

Apparatuses that enable input with a gesture to a computer or anelectronic device are becoming increasingly popular.

For example, Japanese Patent Application Laid-open No. 2012-123608describes an input apparatus configured to capture an image of a gestureperformed by a user in a space using a camera or the like and to convertthe gesture into an input command.

The apparatus stores a specific gesture and a specific input command inassociation with each other and includes a unit configured to recognizea gesture and a unit configured to convert the recognized gesture intoan input command. Accordingly, a user can input an arbitrary commandwithout having to directly operate an input device by simply performinga gesture action in front of the apparatus.

SUMMARY OF THE INVENTION

With an input apparatus that recognizes a gesture, generally, a pointthat represents a position of a part performing a gesture (hereinafter,a representative point) is extracted from an image of the part, and amotion of the extracted representative point is tracked to determinewhat kind of gesture had been performed. For example, when a userperforms a gesture of drawing a graphic by opening the palm of a hand,by detecting a center point of the hand and tracking a locus of thecenter point, a shape of the graphic drawn by the gesture is recognized.

However, when performing a gesture using a hand, setting arepresentative point at the center of the hand may not always be thebest option. For example, when a gesture is performed by raising anindex finger, a recognition result that is more natural to the user canbe obtained by tracking a fingertip of the index finger. In such a case,setting a representative point to the center of the hand creates a riskthat a correct input cannot be made when only a fingertip is movedinstead of making a large motion with the hand.

When performing a gesture using only a part of the body as describedabove, a conventional gesture recognition apparatus cannot alwaysappropriately determine where a representative point is set and, as aresult, cannot always recognize a locus expressed by a gesture asintended by the user.

The present invention has been made in consideration of the problemdescribed above and an object thereof is to provide a technique thatenables a gesture recognition apparatus configured to recognize agesture performed by a user by moving an object part to recognize agesture as intended by the user.

In order to solve the problems described above, the gesture recognitionapparatus according to the present invention is configured to determinea shape of an object part that is a body part to perform a gesture andto determine a position of a representative point in consideration ofthe shape.

Specifically, a gesture recognition apparatus according to the presentinvention is a gesture recognition apparatus detecting a gesture from anacquired image and generating for an object device an instructioncorresponding to the gesture, the gesture recognition apparatusincluding: an image acquiring unit configured to acquire an image; anobject part extracting unit configured to extract an object part toperform a gesture from the acquired image; an object part shapeidentifying unit configured to identify a shape of the extracted objectpart; a representative point determining unit configured to set, withrespect to the object part, a representative point that is a pointrepresenting a position of the object part; a gesture recognizing unitconfigured to recognize a gesture, based on a motion of therepresentative point; and a command generating unit configured togenerate an instruction corresponding to the recognized gesture, whereinthe representative point determining unit determines a position of arepresentative point corresponding to the object part, using theidentified shape of the object part.

An object part refers to a part of a user which is used to perform agesture and which is typically a human hand. However, alternatively, anobject part maybe an entire human body, a marker for inputting that isowned by the user, or the like. While an input gesture can be recognizedby tracking a motion of a representative point corresponding to anobject part, with the gesture recognition apparatus according to thepresent invention, a position of a representative point of an objectpart is determined using a shape of the object part.

In this manner, the gesture recognition apparatus according to thepresent invention determines a position of a representative point inconsideration of a shape of an object part. Accordingly, a gesture inputby moving an object part can be recognized as intended by a user.

In addition, the representative point determining unit may be configuredto set a representative point at a tip of the protruding part when theshape of the object part as identified by the object part shapeidentifying unit is a shape including a protruding part.

When an object part has a partially-protruding shape, it is likely thata gesture is to be input by a motion of the protruding part. Examplesinclude a case where the user is raising at least one of his or herfingers and a case where the user is holding a rod-like input marker. Insuch a case, a representative point is favorably set at a tip of thepart.

Furthermore, the object part may be a human hand, and the representativepoint determining unit may be configured to determine whether the shapeof the object part as identified by the object part shape identifyingunit is a first shape or a second shape that differs from the firstshape, to set a representative point at a position corresponding to afingertip when the shape of the object part is the first shape, and toset a representative point at a position corresponding to a center of ahand when the shape of the object part is the second shape.

When the object part is a human hand, there are two conceivable cases,namely, a case where a gesture is performed using a fingertip and a casewhere a gesture is performed using the entire hand. Therefore, aposition of a representative point is favorably on a fingertip or at thecenter of the hand.

When it is presumed that a gesture is being performed using a fingertipinstead of the entire hand, a representative point is set at a positioncorresponding to the fingertip. Accordingly, a gesture can be recognizedas intended by the user even when the gesture is performed with a smallmotion of a fingertip.

In addition, the representative point determining unit may be configuredto determine that a shape of a hand that is an object part as identifiedby the object part shape identifying unit is a first shape when at leastone of the fingers is extended and to determine that a shape of a handthat is an object part as identified by the object part shapeidentifying unit is a second shape when all of the fingers are extendedor all of the fingers are folded. Furthermore, the representative pointdetermining unit may be configured to determine that a shape of a handthat is an object part is a first shape when only one finger isextended.

When at least one of five fingers is extended, it is presumable that agesture is being performed using a fingertip. In addition, when all ofthe fingers are extended or all of the fingers are folded, it ispresumable that a gesture is being performed by moving the entire hand.Furthermore, when only one extended finger is detected, it is presumablethat a gesture is being performed by using a fingertip. Moreover, it isassumed that a state where at least one of the fingers is extended doesnot include a state where all of the fingers are unfolded.

In addition, the representative point determining unit may be configuredto use a center of gravity of a region corresponding to the hand asextracted by the object part extracting unit as a position correspondingto the center of the hand.

A center of gravity that can be readily calculated is favorably used asa position corresponding to the center of the hand.

Furthermore, the gesture recognition apparatus according to the presentinvention may further include a notifying unit configured to notify theuser of a set position of a representative point.

Examples of the notifying unit include a display apparatus and a soundoutput apparatus. For example, where a representative point is set maybe displayed on a screen. By adopting such a configuration, the user canbe informed as to where a point that is being tracked by the gesturerecognition apparatus is and usability can be further improved.

Moreover, the present invention can be identified as a gesturerecognition apparatus including at least a part of the units describedabove. The present invention can also be identified as a control methodof the gesture recognition apparatus, a program that causes the gesturerecognition apparatus to be operated, and a recording medium on whichthe program is recorded. The processes and units described above may beimplemented in any combination insofar as technical contradictions donot occur.

According to the present invention, with a gesture recognition apparatusthat recognizes a gesture performed by a user by moving an object part,a gesture can be recognized as intended by the user.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a configuration diagram of a gesture recognition systemaccording to a first embodiment;

FIG. 2 is a diagram explaining an example of gesture definition data;

FIG. 3 is a diagram explaining an example of object part extraction;

FIGS. 4A and 4B are diagrams explaining a difference in shapes of objectparts;

FIG. 5 is a flow chart representing processing performed by a gesturerecognition apparatus in the first embodiment;

FIG. 6 is a flow chart representing processing performed by a gesturerecognition apparatus in the first embodiment; and

FIGS. 7A and 7B are diagrams showing examples of a notification screenaccording to a second embodiment.

DESCRIPTION OF THE EMBODIMENTS First Embodiment

An outline of a gesture recognition system according to the firstembodiment will be described with reference to FIG. 1 which is a systemconfiguration diagram. The gesture recognition system according to thefirst embodiment is a system constituted by a gesture recognitionapparatus 100 and an object device 200.

The gesture recognition apparatus 100 is an apparatus configured torecognize a gesture performed by a user using a camera and to generate acommand corresponding to the gesture and to transmit the gesture to theobject device 200.

In addition, the object device 200 is an apparatus (a device that is acontrol object) configured to receive a command from the gesturerecognition apparatus 100 and is typically an electric appliance such asa television set, a video recorder, a computer, an air conditioner, anda teleconference system. The object device 200 may be any kind of deviceas long as a command can be received from the gesture recognitionapparatus 100 in a wired or wireless manner. In the present embodiment,it is assumed that the object device 200 is a television receiver andthat the gesture recognition apparatus 100 is an apparatus that is builtinto the television receiver.

The gesture recognition apparatus 100 will now be described in detail.The gesture recognition apparatus 100 includes an image acquiring unit101, a gesture extracting unit 102, a gesture recognizing unit 103, anda command generating unit 104.

The image acquiring unit 101 is a unit configured to externally acquirean image. In the present embodiment, an image of a user is capturedusing a camera (not shown) attached to an upper part of the front of atelevision screen. The camera used by the image acquiring unit 101 maybe a camera that acquires an RGB image or a camera that acquires agrayscale image or an infrared image. In addition, an image need notnecessarily be acquired by a camera and, for example, an image which isgenerated by a distance sensor and which represents a distancedistribution (distance image) may be used instead. Alternatively, acombination of a distance sensor and a camera or the like may beadopted.

An image acquired by the image acquiring unit 101 (hereinafter, a cameraimage) may be any kind of image as long as the image enables a motion ofa gesture performed by the user and a shape of a body part havingperformed the gesture to be acquired. In addition, an angle of view ofthe camera image may be approximately the same as a viewing angle of thetelevision receiver.

The gesture extracting unit 102 is a unit configured to detect a bodypart (hereinafter, an object part) that performs a gesture from a cameraimage acquired by the image acquiring unit 101. In the presentembodiment, it is assumed that the user is to perform a gesture using ahand. For example, the gesture extracting unit 102 detects a regionrepresenting a human hand from a camera image.

In addition, with respect to a detected object part, the gestureextracting unit 102 sets a representative point that is a pointrepresenting a position of the object part and tracks a motion of therepresentative point. Accordingly, a motion expressed by a gesture canbe extracted.

A shape and a representative point of an object part will be describedin detail later.

The gesture recognizing unit 103 is a unit configured to identifycontents of a gesture based on the motion of the representative pointextracted by the gesture extracting unit 102. For example, the gesturerecognizing unit 103 stores data (gesture definition data) associating amotion of a representative point with contents of a gesture as shown inFIG. 2 and identifies an instruction expressed by a gesture. With aninstruction expressed by a gesture, as shown in FIG. 2, a series ofgesture actions may correspond to a single instruction or an instructionmay cause a pointer displayed on a screen to be moved based on amovement amount and a movement direction of the representative point.

The command generating unit 104 is a unit configured to generate acommand corresponding to the gesture identified by the gesturerecognizing unit 103. A command refers to a signal for controlling theobject device 200 and may be an electric signal, a signal modulated byradio, a pulse-modulated infrared signal, or the like.

The gesture recognition apparatus 100 is a computer including aprocessor, a main storage device, and an auxiliary storage device. Therespective units described above function when a program stored in theauxiliary storage device is loaded to the main storage device andexecuted by the processor (the processor, the main storage device, andthe auxiliary storage device are not shown).

Next, a gesture recognition process will be described in detail.

FIG. 3 shows an example of an image acquired by the image acquiring unit101. Specifically, FIG. 3 depicts a user directly facing a televisionscreen as viewed from the screen.

A gesture recognition process is constituted by a process of detectingan object part to perform a gesture from an image, a process of settinga representative point corresponding to the detected object part, and aprocess of identifying contents of the gesture by tracking a motion ofthe representative point.

First, detection of an object part will be described.

The gesture extracting unit 102 detects a region (reference numeral 31)including a human hand from an acquired image. For example, a regionincluding a human hand may be determined based on color or shape or maybe determined by detecting a feature point. Alternatively, a regionincluding a human hand may be determined by a comparison with a model, atemplate, or the like stored in advance. Since known techniques can beused for hand detection, a detailed description will be omitted.

Next, a representative point will be described.

A representative point is a point representing a position of an objectpart and one representative point is to be set for one object part. Forexample, when the object part is a human hand, a point (referencenumeral 32) representing a center of a palm of the hand can be used asthe representative point.

By setting a representative point to an object part and tracking amotion of the representative point, a gesture expressed by a motion ofthe hand can be acquired. For example, gestures such as “moving anentire hand to indicate a direction” and “drawing a graphic” can beacquired.

Problems found in conventional art will now be described with referenceto FIGS. 4A and 4B.

FIGS. 4A and 4B show examples of a camera image (parts other than anobject part are not illustrated). FIG. 4A represents a gesture thatinvolves moving a fingertip of an index finger while FIG. 4B representsa gesture that involves moving the palm of the hand horizontally.

Although the two gestures both signify “a movement to the left”, agesture performed by raising a finger often represents an attempt toperform a gesture with a fine motion of a fingertip while a gestureperformed by an unfolded hand often represents an attempt to perform agesture with a large motion of an entire arm. Therefore, recognitionaccuracy of a gesture changes depending on which portion of an objectpart a representative point is set to.

For example, in the case of FIG. 4A, a movement distance is a distanceindicated by reference numeral 41 when the representative point is setto the fingertip of the index finger while the movement distance is adistance indicated by reference numeral 42 when the representative pointis set to the center of the palm of the hand. In other words, when adifferent command is assigned by the movement distance, there is a riskthat a command that differs from a desired command is input erroneously.In addition, when moving a pointer in accordance with the movementdistance, there is a risk that a movement amount desired by the user isnot obtained.

In consideration thereof, with the gesture recognition apparatusaccording to the present embodiment, recognition accuracy of a gestureis improved by determining a position of a representative point using ashape of an object part.

In the present embodiment, shapes of an object part are distinguishedaccording to the number of raised fingers. For example, in the case ofFIG. 4A, the number of raised fingers is determined to be one and, inthe case of FIG. 4B, the number of raised fingers is determined to befive. In the following description, a state where one finger is raisedwill be referred to as “shape type 1” and a state where five fingers areraised will be referred to as “shape type 5” . In addition, it isassumed that “shape type n” signifies that there are n-number of raisedfingers.

The number of raised fingers may be determined by, for example,searching for a pointed shape (or a protruding part) that is seemingly afinger in a periphery of a detected hand or by performing matching usinga template image, a hand skeleton model, or the like. Since knownmethods can be used to determine the number of fingers, a detaileddescription will be omitted.

In the present embodiment, when the gesture extracting unit 102determines a shape of a hand and the shape causes a determination that agesture is being performed by a fingertip to be made, a representativepoint is set at a position corresponding to the fingertip. In othercases, a representative point is set to a center of gravity of thedetected hand. A shape causing a determination that a gesture is beingperformed by a fingertip to be made can be, for example, a case wherethe number of raised fingers is one (a case where the shape of theobject part is “shape type 1”).

Next, entire processing performed by the gesture recognition apparatus100 according to the present embodiment will be described with referenceto FIGS. 5 and 6 that are processing flow charts.

The processing shown in FIG. 5 is processing performed by the imageacquiring unit 101 and the gesture extracting unit 102. The processingmay be started when an operation representing a start of input (forexample, when a function requiring a gesture input is started on theobject device) is performed or when power of the object device is turnedon.

First, the image acquiring unit 101 acquires a camera image (step S11).In the present step, for example, an RGB image is acquired using acamera provided in an upper part of the front of the television screen.

Next, the gesture extracting unit 102 attempts to detect an object part(a hand) from the acquired camera image (step S12). As describedearlier, the detection of an object part may be performed based on coloror shape or may be performed by pattern matching or the like. At thispoint, when an object part is not detected, a new image is acquiredafter standing by for a prescribed period of time and similar processingis repeated.

Next, the gesture extracting unit 102 determines a shape of the detectedobject part (step S13). In the present example, a determination is madeon whether the shape of the object part is shape type 1 or another shapetype. If the shape of the object part is a shape type other thanpredefined shape types, the processing may be suspended and a return maybe made to step S11 or a determination of “not applicable” maybe made tocontinue the processing.

Next, a determination is made on whether the detected shape of theobject part has changed from a previous execution (step S14). When stepS14 is executed for the first time, a determination of “changed” ismade.

When a determination of “changed” is made in step S14, a transition ismade to step S15 and the gesture extracting unit 102 sets arepresentative point on the detected object part. Specifically, when theshape of the object part determined in step S13 is shape type 1, arepresentative point is set at a tip of an extended finger, and when theshape is another shape type, a representative point is set to acenter-of-gravity point of the hand.

When a determination of “unchanged” is made in step S14, a transition ismade to step S16.

Next, the gesture extracting unit 102 acquires coordinates of arepresentative point in the camera image and transmits the coordinatesto the gesture recognizing unit 103 (step S16).

The processes of steps S11 to S16 are repetitively executed andcoordinates of representative points are sequentially transmitted to thegesture recognizing unit 103.

The processing shown in FIG. 6 is processing performed by the gesturerecognizing unit 103 and the command generating unit 104. This processis started at the same time as the processing shown in FIG. 5.

Step S21 is a process in which the gesture recognizing unit 103recognizes a gesture based on acquired coordinates of a representativepoint. For example, when the gesture definition data shown in FIG. 2 isavailable and a detection is made that the coordinates of therepresentative point has moved rightward by 100 pixels or more, it isdetermined that a gesture representing “turn up volume” has beenperformed.

Moreover, information transmitted from the gesture extracting unit 102to the gesture recognizing unit 103 need not necessarily be coordinatesin a camera image as long as a movement direction and a movement amountof a representative point can be represented. For example, theinformation may be a conversion of coordinates of a representative pointto a coordinate system having the user as its origin or other datarepresenting a movement direction and a movement amount.

In addition, information representing a size of an object part in acamera image may be simultaneously transmitted. Since a movement amountof an object part acquired by the gesture recognition apparatus changesin accordance with a distance between the user and the apparatus,transmitting such information enables the movement amount to becorrected in accordance with the size of the object part.

Next, the command generating unit 104 generates a control signalcorresponding to the recognized gesture and transmits the control signalto the object device 200 (step S22). In the example described above, forexample, a control signal associated with a “turn up volume” instruction(a signal that turns up the volume by one level) is generated andtransmitted to the object device 200.

The processing shown in FIGS. 5 and 6 is periodically executed and areended when an operation representing an end of input (for example, whenan operation using gesture input is ended on the object device) isperformed.

As described above, the gesture recognition apparatus according to thefirst embodiment sets a position of a representative point to adifferent position according to a shape of an object part havingperformed a gesture. Accordingly, regardless of whether a gesture isbeing performed using a fingertip or an entire hand, the gesture can beaccurately recognized.

Moreover, while the shape of an object part is determined in step S13 inthe description of the present embodiment, a configuration may beadopted in which step S13 is executed only once after detecting anobject part and is skipped after a gesture is started. By adopting sucha configuration, an amount of processing can be reduced.

However, there may be cases where a gesture ends and a different gestureis started in succession. In such a case, a configuration may be adoptedin which step S13 is executed once again. For example, when a shape or asize of an object part changes significantly or when an object partmoves out of frame of an image and subsequently reenters the frame, adetermination that a different gesture has been started may be made andstep S13 may be executed once again. Alternatively, step S13 may beexecuted once again in accordance with an explicit operation.

Second Embodiment

The second embodiment is an embodiment which adds a unit configured tonotify a position of a representative point to a user to the gesturerecognition system according to the first embodiment. A configuration ofa gesture recognition system according to the second embodiment issimilar to that of the first embodiment with the exception of the pointsdescribed below.

While a flow chart of processing performed by a gesture recognitionapparatus 100 according to the second embodiment is similar to FIGS. 5and 6, the processing differs from that shown in FIGS. 5 and 6 in that,when an object part is set in step S15, the gesture extracting unit 102notifies a user of a position where a representative point is setthrough a screen (in the present example, a television screen) providedon an object device 200.

FIGS. 7A and 7B show examples of images displayed on a screen of atelevision receiver that is an object device. For example, when adetected shape of an object part is shape type 1, the fact that agesture can be performed by moving a fingertip is notified, and when thedetected shape is another shape type, the fact that a gesture can beperformed by moving an entire hand is notified.

Moreover, other methods may be used to notify the user. For example,guidance may be displayed using text only or a window for guidance maybe added to an ordinary operation screen to display graphics and text.Alternatively, a notification may be performed by sound or the like.

According to the second embodiment, since the user can recognize where arepresentative point that is tracked by the system is located, gestureinput can be performed more intuitively.

Modifications

It is to be understood that the descriptions of the respectiveembodiments merely represent examples of the present invention and, assuch, the present invention can be implemented by appropriatelymodifying or combining the embodiments without departing from the spiritand the scope of the invention.

For example, while the gesture recognition apparatus 100 has beenassumed to be an apparatus that is built into the object device 200 inthe description of the embodiments, the gesture recognition apparatus100 may alternatively be an independent apparatus.

In addition, the gesture recognition apparatus 100 may be implemented asa program that runs on the object device 200. When implementing thegesture recognition apparatus 100 as a program, a configuration in whicha program stored in a memory is executed by a processor or aconfiguration in which the program stored in the memory is executed by afield programmable gate array (FPGA) or an application specificintegrated circuit (ASIC) may be adopted.

Furthermore, while an example where an image is acquired using a camerahas been presented in the description of the embodiments, an image maybe acquired by other methods including receiving an image via a networkas long as a gesture can be acquired and, at the same time, a shape ofan object part can be distinguished.

Moreover, the object part need not necessarily be a human hand. Forexample, the object part may be another body part, a marker forinputting a gesture, or the like.

When using a marker, the gesture extracting unit 102 may be configuredto detect the presence of the marker and to set a representative pointat a tip of the marker.

In addition, a “shape of an object part” as described in the presentinvention refers to a shape recognized by the gesture recognitionapparatus through an image and need not necessarily be a physicaldeformation of the object part.

Furthermore, while two shape types, namely, “shape type 1” and “anothershape type” are distinguished as shapes of an object part in thedescription of the embodiments, other shapes may be distinguished.Examples of such other shapes may include a closed hand and a statewhere two fingers are raised. Alternatively, three or more shapes may bedistinguished. In any case, a position of a representative point may bedetermined based on a distinguished shape and processing may beperformed according to the method described earlier.

For example, positions where a representative point is set may bedefined as follows.

In case of shape type 0: center of gravity of first is representativepoint

In case of shape type 1: fingertip of raised finger is representativepoint

In case of shape type 2: midpoint between fingertips of two raisedfingers is representative point

In case of shape type 3: fingertip of middle finger among three raisedfingers is representative point

In case of shape types 4 and 5: center of gravity of palm of hand isrepresentative point

In addition, while an object part is detected from a camera image instep S12 and a shape of the object part is subsequently distinguished instep S13 in the description of the respective embodiments, theseprocesses may be simultaneously executed by template matching or thelike. Contents and a processing order of the processes are notparticularly limited as long as a position where an object part ispresent and a shape of the object part can be acquired.

LIST OF REFERENCE NUMERALS

-   100: Gesture recognition apparatus-   101: Image acquiring unit-   102: Gesture extracting unit-   103: Gesture recognizing unit-   104: Command generating unit-   200: Object device

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of Japanese Patent Application No.2014-048911, filed on Mar. 12, 2014, which is hereby incorporated byreference herein in its entirety.

What is claimed is:
 1. A gesture recognition apparatus detecting agesture from an acquired image and generating for an object device aninstruction corresponding to the gesture, the gesture recognitionapparatus comprising: an image acquiring unit configured to acquire animage; an object part extracting unit configured to extract an objectpart performing a gesture from the acquired image; an object part shapeidentifying unit configured to identify a shape of the extracted objectpart; a representative point determining unit configured to set, withrespect to the object part, a representative point that is a pointrepresenting a position of the object part; a gesture recognizing unitconfigured to recognize a gesture, based on a motion of therepresentative point; and a command generating unit configured togenerate an instruction corresponding to the recognized gesture, whereinthe representative point determining unit determines a position of arepresentative point corresponding to the object part, using theidentified shape of the object part.
 2. The gesture recognitionapparatus according to claim 1, wherein the representative pointdetermining unit is configured to set a representative point at a tip ofthe protruding part when the shape of the object part as identified bythe object part shape identifying unit is a shape including a protrudingpart.
 3. The gesture recognition apparatus according to claim 1, whereinthe object part is a human hand, and the representative pointdetermining unit is configured to determine whether the shape of theobject part as identified by the object part shape identifying unit is afirst shape or a second shape that differs from the first shape, to seta representative point at a position corresponding to a fingertip whenthe shape of the object part is the first shape, and to set arepresentative point at a position corresponding to a center of a handwhen the shape of the object part is the second shape.
 4. The gesturerecognition apparatus according to claim 3, wherein the representativepoint determining unit is configured to determine that a shape of a handthat is an object part as identified by the object part shapeidentifying unit is a first shape when at least one of the fingers isextended and to determine that a shape of a hand that is an object partas identified by the object part shape identifying unit is a secondshape when all of the fingers are extended or all of the fingers arefolded.
 5. The gesture acquiring apparatus according to claim 3, whereinthe representative point determining unit is configured to determinethat a shape of a hand that is an object part as identified by theobject part shape identifying unit is a first shape when only one fingeris extended.
 6. The gesture acquiring apparatus according to claim 3,wherein the representative point determining unit is configured to use acenter of gravity of a region corresponding to the hand as extracted bythe object part extracting unit as a position corresponding to thecenter of the hand.
 7. The gesture recognition apparatus according toclaim 1, further comprising a notifying unit configured to notify a userof a set position of a representative point.
 8. A control method of agesture recognition apparatus detecting a gesture from an acquired imageand generating for an object device an instruction corresponding to thegesture, the control method comprising: acquiring an image; extractingan object part performing a gesture from the acquired image; identifyinga shape of the extracted object part; setting, with respect to theobject part, a representative point that is a point representing aposition of the object part; recognizing a gesture, based on a motion ofthe representative point; and generating an instruction corresponding tothe recognized gesture, wherein the setting of the representative pointinvolves determining a position of a representative point correspondingto the object part, using the identified shape of the object part.
 9. Anon-transitory computer readable storing medium recording a computerprogram for causing a computer to perform the respective steps of thecontrol method of a gesture recognition apparatus according to claim 8.